I wouldn't get locked into the idea that a chanter HAS to tune right at a particular pitch. I think it's a ballpark estimate of where it will tune nicely - the range could be 5-6 Hz either way, maybe more, depending upon your environment (humidity, temperature, altitude, etc.).

The band I play with has McCallum MkII's that tune anywhere from Low A = 468-480, depending upon the time of year. When we tune the band, we play just our chanters for a few minutes to get the reeds warmed up, get a reference pitch from one of our more solid players, and tune everybody to that.

Once again, congrats for a successful presentation.